Environmental Safety

52 ProfessionalSafety OCTOBER 2011 www.asse.org

Reviewing Heinrich

Dislodging Two Myths From the Practice of Safety

By Fred A. Manuele

I n The Standardization of Error, Stefansson (1928) makes the case that people are willing to accept as fact what is written or spoken with-

out adequate supporting evidence. When studies show that a supposed fact is not true, dislodging it is difficult because that belief has become deeply embedded in the minds of people and, thereby,

standardized. Stefansson pleads for a

mind-set that accepts as knowledge only that which can be proven and which cannot be logically cont r a - d i c t e d . H e s t a t e s t h a t his theme applies to all fields of endeavor except for mathematics. Safety is a professional specialty in which myths have become standardized and deeply embedded. This article ex- amines two myths that should be dislodged from the practice of safety:

1) Unsafe acts of workers are the principle causes of occupational accidents.

2) Reducing accident fre- quency will equivalently re- duce severe injuries.

These myths arise from the work of H.W. Heinrich (1931; 1941; 1950; 1959).

They can be found in the four editions of Indus- trial Accident Prevention: A Scientific Approach. Although some safety practitioners may not rec- ognize Heinrich’s name, his misleading prem- ises are perpetuated as they are frequently cited in speeches and papers.

Analytical evidence indicates that these prem- ises are not soundly based, supportable or valid, and, therefore, must be dislodged. Although this article questions the validity of the work of an au- thor whose writings have been the foundation of safety-related teaching and practice for many de- cades, it is appropriate to recognize the positive ef- fects of his work as well.

This article was written as a result of encourage- ment from several colleagues who encountered situations in which these premises were cited as fact, with the resulting recommended preventive actions being inappropriate and ineffective. Safety professionals must do more to inform about and refute these myths so that they may be dislodged.

Recognition: Heinrich’s Achievements Heinrich was a pioneer in the field of accident

prevention and must be given his due. Publica- tion of his book’s four editions spanned nearly 30 years. From the 1930s to today, Heinrich likely has had more influence than any other individual on the work of occupational safety practitioners. In retrospect, knowing the good done by him in promoting greater attention to occupational safety and health should be balanced with an awareness of the misdirection that has resulted from applying some of his premises.

Heinrich’s Sources Unavailable

Attempts were made to locate Heinrich’s research, without success. Dan Petersen, who with Nestor Roos, authored a fifth edition of Industrial Accident Prevention, was asked whether they had located Heinrich’s research. Petersen said that they had to

IN BRIEF •This article identifies two myths derived from the work of H.W. Heinrich that should be dislodged from the prac- tice of safety: 1) unsafe acts of workers are the principal causes of occupational accidents; and 2) reducing accident requency will equivalently reduce severe injuries. •As knowledge has evolved about how accidents occur and their causal factors, the emphasis is now correctly placed on improving the work system, rather than on worker behavior. Hein- rich’s premises are not compatible with current thinking. •A call is issued to safety profession- als to stop using and promoting these premises; to dispel these premises in presentations, writings and discussions; and to apply current methods that look beyond Heinrich’s myths to determine true causal factors of incidents.

Fred A. Manuele, P.E., CSP, is president of Hazards Limited, which he formed after retiring from Marsh & McLennan where he was a managing director and manager of M&M Protection Consultants. His books include Advanced Safety Management: Focusing on Z10 and Serious Injury Prevention, On the Practice of Safety, Innovations in Safety Management: Addressing Career Knowledge Needs, and Heinrich Revisited: Truisms or Myths. A professional member of ASSE’s North- eastern Illinois Chapter and an ASSE Fellow, Manuele is a former board member of ASSE, NSC and BCSP.

Professional Development Peer-Reviewed

www.asse.org OCTOBER 2011 ProfessionalSafety 53

rely entirely on the previous editions of

Heinrich’s books as resources. Thus, the only

data that can be reviewed are contained in Heinrich’s

books. His information-gather- ing methods, survey documents

that may have been used, the qual- ity of the information gathered and the

analytical systems used cannot be examined. Two items of note for this article: Citations from

Heinrich’s texts are numbered H-1, H-2, etc., and correspond to the chart in Table 1, which indicates the page numbers and editions in which each ci- tation appears. All other citations appear as in-text references in the journal’s standard style.

Furthermore, in today’s social climate, some of Heinrich’s terminology would be considered sex- ist. He uses phrases such as man failure, the foreman and he is responsible. Consider the time in which he wrote. The fourth edition was published in 1959.

Psychology & Safety Applied psychology dominates Heinrich’s work

with respect to selecting causal factors and is given great importance in safety-related problem resolu- tion. Consider the following:

1) Heinrich expresses the belief that “psy- chology in accident prevention is a fundamen- tal of great importance” (H-1).

2) His premise is that “psychology lies at the root of sequence of accident causes” (H-2).

3) In the fourth edition, Heinrich states that he envisions “the more general acceptance by man- agement of the idea that an industrial psycholo- gist be included as a member of the plant staff as a physician is already so included” (H-3).

4) The focus of applied psychology on the em- ployee, as in the following quotation:

Indeed, safety psychology is as fairly appli- cable to the employer as to the employee. The initiative and the chief burden of ac- tivity in accident prevention rest upon the employer; however the practical field of effort for prevention through psychology is confined to the employee, but through management and supervision. (H-4)

Note that the focus of applied psychology is on the worker as are other Heinrichean premises. Since application of practical psychology is confined to the worker, who reports to a supervisor, the psy- chology applier is the supervisor. With due respect to managers, supervisors and safety practitioners, it is doubtful that many could knowledgeably apply psychology “as a fundamental of great importance” in their accident prevention efforts.

Table 1

Pages Cited by Edition

54 ProfessionalSafety OCTOBER 2011 www.asse.org

Heinrich’s Causation Theory: The 88-10-2 Ratio Heinrich professes that among the direct and

proximate causes of industrial accidents: •88% are unsafe acts of persons; •10% are unsafe mechanical or physical condi-

tions; •2% are unpreventable (H-5). According to Heinrich, man failure is the problem

and psychology is an important element in correct- ing it. In his discussion of the relation of psychology to accident prevention, Heinrich advocates identi- fying the first proximate and most easily prevented cause in the selection of remedies. He says:

Selection of remedies is based on practical cause-analysis that stops at the selection of the first proximate and most easily prevented cause (such procedure is advocated in this book) and considers psychology when re- sults are not produced by simpler analysis. (H-6)

Note that the first proximate and most easily prevented cause is to be selected (88% of the time a human error). That concept permeates Hein- rich’s work. It does not encompass what has been learned subsequently about the complexity of ac- cident causation or that other causal factors may be more significant than the first proximate cause.

For example, the Columbia Accident Investiga- tion Board (NASA, 2003) notes the need to con- sider the complexity of incident causation:

Many accident investigations do not go far enough. They identify the technical cause of the accident, and then connect it to a vari- ant of “operator error.” But this is seldom the entire issue. When the determinations of the causal chain are limited to the technical flaw and individual failure, typically the actions taken to prevent a similar event in the future are also limited: fix the technical problem and replace or retrain the individual responsible.

Putting these corrections in place leads to another mistake: The belief that the problem is solved. Too often, accident investigations blame a failure only on the last step in a com- plex process, when a more comprehensive understanding of that process could reveal that earlier steps might be equally or even more culpable.

A recent example of the complexity of accident causation appears in this excerpt from the report prepared by BP personnel following the April 20, 2010, Deepwater Horizon explosion in the Gulf of Mexico (BP, 2010):

The team did not identify any single action or inaction that caused this incident. Rather, a complex and interlinked series of mechanical failures, human judgments, engineering de- sign, operational implementation and team interfaces came together to allow the initia- tion and escalation of the accident.

Consider another real-world situation in which a fatality resulted from multiple causal factors:

An operation produces an odorless, color- less highly toxic gas in an enclosed area. The two-level gas detection and alarm system has deteriorated over many years of use, and the system often leaks gas. An internal auditor recommends it be replaced with a three-level system, the accepted practice in the industry for that type of gas. The auditor also recommends that maintenance give the existing system high priority.

Management puts high profits above safety and tolerates excessive risk taking. That defines culture problems. Management decides not to replace the system, and fur- thermore begins a cost-cutting initiative that reduces maintenance staff by one-third. The gas detection and alarm system continue to deteriorate, and maintenance staff cannot keep up with the frequent calls for repair and adjustment.

A procedure is installed that requires employees to test for gas before entering the enclosed area. But, supervisors condone employees entering the area without making the required test. Both detection and alarm systems fail. Gas accumulates. An employee enters the area without testing for gas. The result is a toxic gas fatality.

Causal factor determination would com- mence with the deficiencies in the organiza- tion’s culture whereby: resources were not provided to replace a defective detection and alarm system in a critical area; staffing deci- sions resulted in inadequate maintenance; and excessive risk taking was condoned. The employee’s violation of the established procedure was a contributing factor, but not principle among several factors.

Heinrich’s theory that an unsafe act is the sole cause of an accident is not supported in the cited examples. Also, note that Heinrich’s focus on man failure is singular in the following citation: “In the occurrence of accidental injury, it is apparent that man failure is the heart of the problem; equally ap- parent is the conclusion that methods of control must be directed toward man failure” (H-7). [Note: Heinrich does not define man failure. In making the case to support directing efforts toward con- trolling man failure, he cites personal factors such as unsafe acts, using unsafe tools and willful disre- gard of instruction.]

A directly opposite view is expressed by Deming (1986). Deming is known for his work in quality principles, which this author finds comparable to the principles required to achieve superior results in safety.

The supposition is prevalent throughout the world that there would be no problems in production or service if only our production workers would do their jobs in the way that we taught. Pleasant dreams. The workers are handicapped by the system, and the system belongs to the management. (p. 134)

Analytical evidence indicates that several of Heinrich’s premis- es, first introduced in 1931, are not soundly based, supportable or

valid, and, therefore, must be dislodged.

www.asse.org OCTOBER 2011 ProfessionalSafety 55

Of all Heinrich’s concepts, his thoughts on ac- cident causation, expressed as the 88-10-2 ratios, have had a significant effect on the practice of safety, and have resulted in the most misdirection. Why is this so? Because when based on the premise that man failure causes the most accidents, preven- tive efforts are directed at the worker rather than toward the operating system in which the work is performed.

Many safety practitioners operate on the belief that the 88-10-2 ratios are soundly based and, as a result, focus their efforts on reducing so-called man failure rather than attempting to improve the system. This belief also perpetuates because it is the path of least resistance for an organization. It is easier for supervisors and managers to be satisfied with taking superficial preventive action, such as retraining a worker, reinstructing the work group or reposting the standard operating procedure, than it is to try to correct system problems.

Certainly, operator errors may be causal factors for accidents. However, consider Ferry’s (1981) comments on this subject:

We cannot argue with the thought that when an operator commits an unsafe act, leading to a mishap, there is an element of human or operator error. We are, however, decades past the place where we once stopped in our search for causes.

Whenever an act is considered unsafe we must ask why. Why was the unsafe act com- mitted? When this question is answered in depth it will lead us on a trail seldom of the operator’s own conscious choosing. (p. 56)

If, during an accident investigation, a professional search is made for causal factors beyond an unsafe act, such as through the five-why method, one will likely find that the causal factors built into work sys- tems may be of greater importance than an employ- ee’s unsafe act. Fortunately, a body of literature has emerged that recognizes the significance of causal factors which originate from decisions made above the worker level. Several are cited here.

Human Errors Above the Worker Level Much has been written about human error. Par-

ticular attention is given to the Guidelines for Pre- venting Human Error in Process Safety (CCPS, 1994). Although process safety appears in the title, the first two chapters provide an easily read primer on hu- man error reduction. The content of those chapters was largely influenced by personnel with plant- or corporate-level safety management experience.

Safety practitioners should view the following highlights as generic and broadly applicable. They advise on where human errors occur, who commits them and at what level, the effect of organizational culture and where attention is needed to reduce the occurrence of human errors. These highlights apply to organizations of all types and sizes.

•It is readily acknowledged that human errors at the operational level are a primary contributor to the failure of systems. It is often not recognized,

however, that these errors frequently arise from failures at the management, design or technical ex- pert levels of the company (p. xiii).

•A systems perspective is taken that views error as a natural consequence of a mismatch between human capabilities and demands, and an inappro- priate organizational culture. From this perspec- tive, the factors that directly influence error are ultimately controllable by management (p. 3).

•Almost all major accident investigations in re- cent years have shown that human error was a significant causal factor at the level of design, op- erations, maintenance or the management process (p. 5).

•One central principle presented in this book is the need to consider the organizational factors that create the preconditions for errors, as well as the immediate causes (p. 5).

•Attitudes toward blame will determine whether an organization develops a blame culture, which attributes error to causes such as lack of motivation or deliberate unsafe behavior (p. 5).

•Factors such as the degree of participation that is encouraged in an organization, and the quality of the communication between different levels of management and the workforce, will have a major effect on the safety culture (p. 5).

Since “failures at the management, design or technical expert levels of the company” affect the design of the workplace and the work methods— that is, the operating system—it is logical to suggest that safety professionals should focus on system improvement to attain acceptable risk levels rather than principally on affecting worker behavior.

Reason’s (1997) book, Managing the Risks of Organizational Accidents, is a must-read for safety professionals who want an education in human er- ror reduction. It has had five additional printings since 1997. Reason writes about how the effects of decisions accumulate over time and become the causal factors for incidents resulting in serious in- juries or major damage when all the circumstances necessary for the occurrence of a major event fit together. This book stresses the need to focus on decision making above the worker level to prevent major accidents. Reason states:

Latent conditions, such as poor design, gaps in supervision, undetected manufacturing defects or maintenance failures, unworkable procedures, clumsy automation, shortfalls in training, less than adequate tools and equip- ment, may be present for many years before they combine with local circumstances and active failures to penetrate the system’s lay- ers of defenses.

They arise from strategic and other top- level decisions made by governments, regulators, manufacturers, designers and or- ganizational managers. The impact of these decisions spreads throughout the organiza- tion, shaping a distinctive corporate culture and creating error-producing factors within the individual workplaces. (p. 10)

56 ProfessionalSafety OCTOBER 2011 www.asse.org

The traditional occupational safety ap- proach alone, directed largely at the unsafe acts of persons, has limited value with re- spect to the “insidious accumulation of la- tent conditions [that he notes are] typically present when organizational accidents occur. (pp. 224, 239)

If the decisions made by management and oth- ers have a negative effect on an organization’s culture and create error-producing factors in the workplace, focusing on reducing human errors at the worker level—the unsafe acts—will not ad- dress the problems.

Deming achieved world renown in quality assur- ance. The principle embodied in what is referred to as Deming’s 85-15 rule also applies to safety. The rule supports the premise that prevention efforts should be focused on the system rather than on the worker. This author draws a comparable conclu- sion as a result of reviewing more than 1,700 inci- dent investigation reports. This is the rule, as cited by Walton (1986): “The rule holds that 85% of the problems in any operation are within the system and are the responsibly of management, while only 15% lie with the worker” (p. 242).

In 2010, ASSE sponsored the symposium, Re- think Safety: A New View of Human Error and Workplace Safety. Several speakers proposed that the first course of action to prevent human errors is to examine the design of the work system and work methods. Those statements support Dem- ing’s 85-15 rule. Consider this statement by a hu- man error specialist [from this author’s notes]:

When errors occur, they expose weakness- es in the defenses designed into systems, processes, procedures and the culture. It is management’s responsibility to anticipate errors and to have systems and work meth- ods designed so as to reduce error potential

and to minimize sever- ity of injury potential when errors occur.

Since most problems in an operation are systemic, safety efforts should be directed to- ward improving the system. Unfortunately, the use of the terms unsafe acts and unsafe conditions focuses attention on a worker or a condition, and diverts attention from the root-causal factors built into an operation.

Allied to Deming’s view is the work of Chapanis, who was prominent in the field of ergonomics and human fac- tors engineering. Represen- tative of Chapanis’s writings is “The Error-Provocative Situation,” a chapter in The Measurement of Safety Perfor- mance (Tarrants, 1980). Cha-

panis’s message is that if the design of the work is error-provocative, one can be certain that errors will occur in the form of accident causal factors. It is illogical to conclude in an incident investigation that the principal causal factor is the worker’s un- safe act if the design of the workplace or the work methods is error-inviting. In such cases, the error- producing aspects of the work (e.g., design, layout, equipment, operations, the system) should be con- sidered primary.

U.S. Department of Energy (1994) describes the management oversight and risk tree (MORT) as a “comprehensive analytical procedure that provides a disciplined method for determining the systemic causes and contributing factors of accidents.” The following reference to “performance errors” is of particular interest.

It should be pointed out that the kinds of questions raised by MORT are directed at systemic and procedural problems. The ex- perience, to date, shows there are a few “un- safe acts” in the sense of blameful work level employee failures. Assignment of “unsafe act” responsibility to a work-level employee should not be made unless or until the pre- ventive steps of 1) hazard analysis; 2) man- agement or supervisory direction; and 3) procedures safety review have been shown to be adequate. (p. 19)

Each of these more recent publications refutes the premise that unsafe acts are the primary causes of occupational accidents.

Heinrich’s Data Gathering & Analytical Method Heinrich recognized that other studies on acci-

dent causation identified both unsafe acts and un- safe conditions as causal factors with almost equal frequency. Those studies produced results different from the 88-10-2 ratios. For example, the Accident

Figure 1

Foundation of a Major Injury

Note. Adapted from Industrial Accident Prevention: A Scientific Approach (1st ed.) (p. 91), (2nd ed.) (p. 27), (3rd ed.) (p. 24), (4th ed.) (p. 27), by H.W. Heinrich, 1931, 1941, 1950, 1959, New York: McGraw-Hill.

Heinrich’s 300-29-1 ratios have been depicted as a tri-

angle or a pyramid.

www.asse.org OCTOBER 2011 ProfessionalSafety 57

Prevention Manual for Industrial Operations: Ad- ministration and Programs, 8th edition (NSC, 1980) contains these statements about studies of accident causation:

Two historical studies are usually cited to pinpoint the contributing factor(s) to an ac- cident. Both emphasize that most accidents have multiple causes.

•A study of 91,773 cases reported in Penn- sylvania in 1953 showed 92% of all nonfatal injuries and 94% of all fatal injuries were due to hazardous mechanical or physical condi- tions. In turn, unsafe acts reported in work injury accidents accounted for 93% of the nonfatal injuries and 97% of the fatalities.

•In almost 80,000 work injuries re- ported in that same state in 1960, unsafe condition(s) was identified as a contributing factor in 98.4% of the nonfatal manufactur- ing cases, and unsafe act(s) was identified as a contributing factor in 98.2% of the nonfatal cases. (p. 241)

Although aware that others studying accident causation had recognized the multifactorial nature of causes, Heinrich continued to justify selecting a single causal factor in his analytical process. Hein- rich’s data-gathering methods force the accident cause determination into a singular and narrow categorization. The following paragraph is found in the second through fourth editions. It follows an explanation of the study resulting in the formula- tion of the 88-10-2 ratios. “In this research, major responsibility for each accident was assigned either to the unsafe act of a person or to an unsafe me- chanical condition, but in no case were both per- sonal and mechanical causes charged” (H-8).

Heinrich’s study resulting in the 88-10-2 ratios was made in the late 1920s. Both the relation- ship of a study made then to the work world as it now exists and the methods used in producing it are questionable and unknown. As to the study methods, consider the following paragraph, which appears in the first edition; minor revisions were made in later editions.

Twelve thousand cases were taken at random from closed-claim-file insurance records. They covered a wide spread of territory and a great variety of industrial classifications. Sixty-three thousand other cases were taken from the records of plant owners. (H-9)

The source of the data was insurance claims files and records of plant owners, which cannot provide reliable accident causal data because they rarely include causal factors. Nor are accident investiga- tion reports completed by supervisors adequate re- sources for causal data. When this author provided counsel to clients in the early stages of developing computer-based incident analysis systems, insur- ance claims reports and supervisors’ investigation reports were examined as possible sources for causal data. It was rare for insurance claims reports to include provisions to enter causal data.

This author has examined more than 1,700 in- cident investigation reports completed by super- visors and investigation teams. In approximately 80% of those reports, causal factor information was inadequate. These reports are not a sound base from which to analyze and conclude with respect to the reality of causal factors.

Summation on the 88-10-2 Ratios Heinrich’s data collection and analytical meth-

ods in developing the 88-10-2 ratios are unsup- portable. Heinrich’s premise, that unsafe acts are the primary causes of occupational accidents, can- not be sustained. The myth represented by those ratios must be dislodged and actively refuted by safety professionals.

An interesting message of support with respect to avoiding use of the 88-10-2 ratios comes from Krause (2005), a major player in worker-focused behavior-based safety:

Many in the safety community believe a high percentage of incidents, perhaps 80% to 90%, result from behavioral causes, while the remainder relate to equipment and facilities. We made this statement in our first book in 1990. However, we now recognize that this dichotomy of causes, while ingrained in our culture generally and in large parts of the safety community, is not useful, and in fact can be harmful. (p. 10)

The Foundation of a Major Injury: The 300-29-1 Ratios Heinrich’s conclusion with respect to the ratios

of incidents that result in no injuries, minor injuries and a major lost-time case was the base on which educators taught and many safety practitioners came to believe that reducing accident frequency will achieve equivalent reduction in injury sever- ity. The following statement appears in all four edi- tions of his text: “The natural conclusion follows, moreover, that in the largest injury group—the minor injuries—lies the most valuable clues to ac- cident causes” (H-10).

The following discussion and statistics establish that the ratios upon which the foregoing citation is based are questionable and that reducing incident frequency does not necessarily achieve an equiva- lent reduction in injury severity. Heinrich’s 300-29-1 ratios have been depicted as a triangle or a pyramid (Figure 1). In his first edition, Heinrich writes:

Analysis proves that for every mishap re- sulting in an injury there are many other ac- cidents in industry which cause no injuries whatever. From data now available concern- ing the frequency of potential-injury acci- dents, it is estimated that in a unit group of 330 accidents, 300 result in no injuries, 29 in minor injuries, and 1 in a major or lost-time case. (H-11)

In the second edition, “similar” was added to the citation: “Analysis proves that for every mishap, there are many other similar accidents in industry . . .” (H-12).

Heinrich’s study resulting in the 88-10-2 ratios was made in the late 1920s. Both the relationship of a study made then to the work world as it now exists and the methods used in producing it are questionable and unknown.

58 ProfessionalSafety OCTOBER 2011 www.asse.org

Within a chart displaying the 300-29-1 ratios in the first edition, Heinrich writes, “The total of 330 accidents all have the same cause.” Note that cause is singular (H-13). This statement, that all 330 in- cidents have the same cause, challenges credulity. Also, note that the sentence quoted in this para- graph appears only in the first edition. It does not appear in later editions (H-14).

For background data, Heinrich says in the first, second and third editions:

The determination of this no-injury accident frequency followed a most interesting and ab- sorbing study [italics added]. The difficulties can be readily imagined. There were few ex- isting data on minor injuries—to say nothing of no-injury accidents. (H-15)

In the fourth edition, published 28 years after the first edition, the source of the data is more specifi- cally stated:

The determination of this no-injury accident frequency followed a study of over 5,000 cases [italics added]. The difficulties can be readily imagined. There were few existing data on minor injuries—to say nothing of no-injury accidents. (H-16)

The credibility of such a revision after 28 years must be questioned. In Heinrich’s second and third editions, major changes were made in his presen- tation on the ratios, without explanation.

1) The statement in the first edition that the 330 accidents all have the same cause was eliminated.

2) In the second edition, changes were made indicating that the unit group of 330 accidents are “similar” and “of the same kind” (H-17).

3) In the third edition, another significant addi- tion is made. The 330 accidents now are “of the same kind and involving the same person” (H-18).

The following appears in the third and fourth editions, encompassing the changes noted.

Analysis proves that for every mishap result- ing in an injury there are many other similar accidents that cause no injuries whatever. From data now available concerning the fre- quency of potential-injury accidents, it is es-

timated that in a unit group of 330 accidents of the same kind and involving the same person [italics added], 300 result in no injuries, 29 in minor injuries and 1 in a major or lost-time injury. (H-19)

These changes are not explained. If the original data were valid, how does one explain the sub- stantial revisions in the conclusions eventually drawn from an analysis of it? In the second, third and fourth editions, Heinrich gives no indication of other data collection activities or of other analy- ses. How does one support using the ratios without having explanations of the differing interpretations Heinrich gives in each edition?

The changes made in the 300-29-1 ratios in the second and third editions, and carried over into the fourth edition, present other serious conceptual problems. To which types of accidents does “in a unit group of 330 accidents of the same kind and occurring to the same person” apply? Certainly, it does not apply to some commonly cited incident types, such as falling to a lower level or struck by objects.

For example, a construction worker rides the hoist to the 10th floor and within minutes backs into an unguarded floor opening, falling to his death. Heinrich’s ratios would give this person fa- vorable odds of 300 to 330 (10 out of 11) of suffer- ing no injury at all. That is not credible.

Consider the feasibility of finding data in the 5,000-plus cases studied to support the ratios, keeping in mind that incidents are to be of the same type and occurring to the same person.

•If the number of major or lost-time cases is 1, the number of minor injury case files would be 29 and the number of no-injury case files would be 300.

•If the number of major or lost-time cases is 5, the number of minor injury case files would be 145 and the number of no-injury case files would be 1,500.

•If the number of major or lost-time cases is 10, the number of minor injury case files would be 290 and the number of no-injury case files would be 3,000.

Because of the limitations Heinrich himself im- poses, that all incidents are to be of the same type and occurring to the same person, it is implausible that his database could contain the information necessary for analysis and the conclusions he drew on his ratios. Particularly disconcerting is the need for the database to contain information on more than 4,500 no-injury cases (300 ÷ 330 × 5,000). Un- less a special study was initiated, creating files on no-injury incidents would be a rarity.

Given this, one must ask, did a database exist upon which Heinrich established his ratios, then stated the premises that the most valuable clues for accident causes are found in the minor injury cat- egory? This author thinks not.

Statistical Indicators: Serious Injury Trending Data on the trending of serious injuries and

workers’ compensation claims contradict the

Table 2

Injury Reduction Categories

Note. Data from “State of the Line,” by National Council on Compensation Insurance, 2005, Boca Raton, FL: Author.

Data on the trending of serious

injuries and workers’ compen- sation claims con- tradict the premise

that focusing on incident frequency

reduction will equiv- alently achieve

severity reduction.

www.asse.org OCTOBER 2011 ProfessionalSafety 59

premise that focusing on incident frequency reduc- tion will equivalently achieve severity reduction. The following data have been extracted from pub- lications of the National Council on Compensation Insurance (NCCI, 2005; 2006; 2009).

•In 2006, NCCI produced a 12-minute video, The Remarkable Story of Declining Frequency— Down 30% in the Past Decade. It shows that work- ers’ compensation claim frequency was down considerably in the decade cited. The video tells a remarkable but not well-known story.

•A July 2009 NCCI bulletin, “Workers’ Compen- sation Claim Frequency Continues Its Decline in 2008.” The reduction was 4.0%. A May 2010 NCCI report says that the cumulative reduction in claims frequency from 1991 through 2008 is 54.7%.

•A 2005 NCCI paper, “Workers’ Compensation Claim Frequency Down Again,” states, “There has been a larger decline in the frequency of smaller lost-time claims than in the frequency of larger lost-time claims.” Also, consider that NCCI (2005) reports reductions in selected categories of claim values for the years 1999 and 2003, expressed in 2003 hard dollars (Table 2).

While the frequency of workers’ compensation cases is down, the greatest reductions are for less serious injuries. The reduction in cases valued from $10,000 to $50,000 is about one-third of that for cases valued at less than $2,000. For cases valued above $50,000, the reduction is about one-fifth of that for the less costly and less serious injuries. The data clearly show that a comparable reduction in injury severity does not follow a reduction in injury frequency.

A DNV (2004) bulletin is another resource of particular note. It states that managing operations to reduce frequency will not equivalently reduce severity.

What about the pyramid? Much has been said over the years about

the classical loss control pyramid, which in- dicates the ratio between no loss incidents, minor incidents and major incidents, and it has often been argued that if you look after the small potential incidents, the major loss incidents will improve also.

The major accident reality however is somewhat different. What we find is that if you manage the small incidents effectively, the small incident rate improves, but the major accident rate stays the same, or even slightly increases.

Contradictions: Unsafe Acts & Injuries Heinrich’s texts contain contradictions about

when a major injury would occur and the relation- ship between unsafe acts and a major injury. In all editions, reference is made to 330 careless acts or several hundred unsafe acts occurring before a ma- jor injury occurs, as in the following examples from the first and third editions.

•“Keep in mind that a careless act occurs ap- proximately 300 times before [italics added] a seri-

ous injury results and that there is, therefore, an excellent opportunity to detect and correct unsafe practices before injury occurs” (H-20).

•“Keep in mind that an unsafe act occurs several hundred times before [italics added] a serious injury results” (H-21).

Before is a key word here. While an unsafe act may be performed several times before a particu- lar accident occurs, that is not the case in a large majority of incidents which result in serious injury or fatality. In his fourth edition, Heinrich gave this view of the relationship of unsafe acts or exposures to mechanical hazards.

If it were practicable to carry on appropriate research, still another base therefore could be established showing that from 500 to 1,000 or more unsafe acts or exposures to mechan- ical hazards existed in the average case be- fore even one of the 300 narrow escapes from injury (events-accidents) occurred. (H-22)

There is a real problem here. All of those unsafe acts or exposures to mechanical hazards take place before even one accident occurs. That is illogical.

Summation on the 300-29-1 Ratios Use of the 300-29-1 ratios is troubling. Since the

ratios are not soundly based, one must ask whether the ratios have any substance. Does their use as a base for a safety management system result in a concentration of resources on the frequent and lesser significant while ignoring opportunities to reduce the more serious injuries?

One of Heinrich’s premises is that “the predomi- nant causes of no-injury accidents are, in average cases, identical with the predominant causes of major injuries, and incidentally of minor injuries as well.” This is wrong. It is a myth that must be dis- lodged from the practice of safety.

Applying this premise leads to misdirection in resource application and ineffectiveness, particu- larly with respect to preventing serious injuries. In this author’s experience, many incidents resulting in serious injury are singular and unique events, with multifaceted and complex causal factors, and descriptions of similar incidents are rare in the his- torical body of incident data. Furthermore, all haz- ards do not have equal potential for harm. Some risks are more significant than others. That requires priority setting.

Misinterpretation of Terms

Not only have many safety practitioners used the 300-29-1 ratios in statistical presentations, but many also have misconstrued what Heinrich in- tended with the terms major injury, minor injury and no-injury accidents. Some practitioners who cite these ratios in their presentations assume that a “major injury” is a serious injury or a fatality. In each edition, Heinrich gave nearly identical defini- tions of the accident categories to which the 300- 29-1 ratios apply. This is how the definition reads in the fourth edition.

In the accident group (330 cases), a major in-

Use of the 300-29-1 ratios is troubling. Applying this premise leads to misdirection in re- source application and ineffectiveness, particularly with re- spect to preventing serious injuries.

60 ProfessionalSafety OCTOBER 2011 www.asse.org

jury is any case that is reported to insurance carriers or to the state compensation com- missioner. A minor injury is a scratch, bruise or laceration such as is commonly termed a first-aid case. A no-injury accident is an un- planned event involving the movement of a person or an object, ray or substance (e.g., slip, fall, flying object, inhalation) having the probability of causing personal injury or property damage. The great majority of re- ported or major injuries are not fatalities or fractures or dismemberments; they are not all lost-time cases, and even those that are do not necessarily involve payment of com- pensation. (H- 20)

These definitions compel the conclusion that any injury requiring more than first-aid treatment is a major injury. When these definitions were devel- oped in the late 1920s, few companies were self-in- sured for workers’ compensation. On-site medical facilities were rare. Insurance companies typically paid for medical-only claims and for minor and major injuries. According to Heinrich’s definitions, almost all such claims would be considered major injuries. Then, is it not so that every OSHA record- able injury is a major injury in this context?

Heinrich’s 300-29-1 ratios have been misused and misrepresented many times as well. For exam- ple, a safety director recently said that in the pre- vious year his company sustained one fatality and 30 OSHA days-away-from-work incidents, and, therefore, Heinrich’s progression was validated. Not so. All of the injuries and the fatality would be in the major or lost-time injury category.

In another instance, a speaker referred to Hein- rich’s 300-29-1 ratios and said that the 300 were unsafe acts, the 29 were serious injuries and the 1 was a fatality. These are but two examples of the many misuses of these ratios.

Heinrich’s Premises Versus Current Safety Knowledge Heinrich emphasized improving an individual

worker’s performance, rather than improving the work system established by management. That is not compatible with current knowledge. Unfortu- nately, some safety practitioners continue to base their counsel on Heinrich’s premises, which nar- rows the scope of their activities as they attempt principally to improve worker performance. In do- ing so, they ignore the knowledge that has evolved in the professional practice of safety. A few exam- ples follow:

•Hazards are the generic base of, and the justi- fication for the existence of, the practice of safety.

•Risk is an estimate of the probability of a haz- ard-related incident or exposure occurring and the severity of harm or damage that could result.

•The entirety of purpose of those responsible for safety, regardless of their titles, is to manage their endeavors with respect to hazards so that the risks deriving from those hazards are acceptable.

•All risks to which the practice of safety applies derive from hazards. There are no exceptions.

•Hazards and risks are most effectively and eco- nomically avoided, eliminated or controlled in the design and redesign processes.

•The professional practice of safety requires con- sideration of the two distinct aspects of risk:

1) avoiding, eliminating or reducing the prob- ability of a hazard-related incident or exposure oc- curring;

2) reducing the severity of harm or damage if an incident or exposure occurs.

•Management creates the safety culture, wheth- er positive or negative.

•An organization’s culture, translated into a system of expected behavior, determines man- agement’s commitment or lack of commitment to safety and the level of safety achieved.

•Principal evidence of an organization’s culture with respect to occupational risk management is demonstrated through the design decisions that determine the facilities, hardware, equipment, tooling, materials, processes, configuration and layout, work environment and work methods.

•Major improvements in safety will be achieved only if a culture change takes place, only if major changes occur in the system of expected behavior.

•While human errors may occur at the worker level, preconditions for the commission of such er- rors may derive from decisions made with respect to the workplace and work methods at the man- agement, design, engineering or technical expert levels of an organization.

•Greater progress can be obtained with respect to safety by focusing on system improvement to achieve acceptable risk levels, rather than through modifying worker behavior.

•A large proportion of problems in an opera- tion are systemic, deriving from the workplace and work methods created by management, and can be resolved only by management. Responsibility for only a relatively small remainder lies with the worker.

•While employees should be trained and em- powered up to their capabilities and encouraged to make contributions with respect to hazard identifi- cation and analysis, and risk elimination or control, they should not be expected to do what they can- not do.

•Accidents usually result from multiple and in- teracting causal factors that may have organiza- tional, cultural, technical or operational systems origins.

•If accident investigations do not relate to actual causal factors, corrective actions taken will be mis- directed and ineffective.

•Causal factors for low-probability/high-conse- quence events are rarely represented in the analyti- cal data on incidents that occur frequently, and the uniqueness of serious injury potential must be ad- equately addressed. However, accidents that occur frequently may be predictors of severity potential if a high energy source was present (e.g., operation of powered mobile equipment, electrical contacts).

As this list demonstrates, Heinrich’s premises are not compatible with current knowledge.

Heinrich empha- sized improving an individual worker’s

performance, rather than improving the

work system estab- lished by manage-

ment. That is not compatible with

current knowledge.

www.asse.org OCTOBER 2011 ProfessionalSafety 61

Conclusion As knowledge has evolved about how accidents

occur and their causal factors, the emphasis is now properly placed on improving the work system, rather than on worker behavior. As one colleague who is disturbed by safety professionals who refer- ence Heinrich premises as fact, says, “It is border- line unethical on their part.”

This article has reviewed the origin of certain premises that have been accepted as truisms by many educators and safety practitioners, and how they evolved and changed over time; it also ex- amined their validity. The two premises discussed here are wrongly based and cannot be sustained by safety practitioners. The premises themselves and the methods used to establish them cannot withstand a logic test. They are myths that have become deeply embedded in the practice of safety and safety professionals must take action to dis- lodge them. PS

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Recommendations Safety professionals should ensure that the Heinrich misconcep-

tions discussed in this article are discarded by the profession. To achieve this, each safety professional should:

•Stop using or promoting the premises that unsafe acts are the primary causes of accidents and that focusing on reducing accident frequency will equivalently reduce injury severity.

•Actively dispel these premises in presentations, writings and discussions.

•Politely but firmly refute allegations by others who continue to promote the validity of these premises.

•Apply current methods that look beyond Heinrich’s myths to determine true causal factors of accidents.

Acknowledgment Parts of this article are updated material from three of the author’s works: Heinrich Revis- ited: Truisms or Myths; chapter seven in On the Practice of Safety (3rd ed.); and the article, “Serious Injuries and Fatalities: A Call for a New Focus on Their Prevention,” from the December 2008 issue of Professional Safety.

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